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Article

Abstract

It is shown that underpotential deposition of zinc from a plating solution inhibited the discharge of hydrogen on HY-130 steel. In the presence of a monolayer coverage of Zn, hydrogen evolution currents were reduced by 58% compared with values obtained on bare HY-130 steel. The observed effects are due to the kinetic limitations of the hydrogen discharge reaction and the suppression of hydrogen absorption by the deposited monolayers. The hydrogen atom direct entry mechanism was used and a mass transfer term was introduced into the permeation model to interpret the experimental data. In the presence of zinc monolayers, the hydrogen entry efficiency in the alloy and the hydrogen entry rate constant were reduced by a factor of three and by 74%, respectively.